public virtual NeoDatis.Btree.IKeyAndValue GetBiggest(NeoDatis.Btree.IBTreeNode node
, bool delete)
{
int lastKeyIndex = node.GetNbKeys() - 1;
int lastChildIndex = node.GetNbChildren() - 1;
if (lastChildIndex > lastKeyIndex)
{
NeoDatis.Btree.IBTreeNode child = node.GetChildAt(lastChildIndex, true);
if (child.GetNbKeys() == degree - 1)
{
node = PrepareForDelete(node, child, lastChildIndex);
}
lastChildIndex = node.GetNbChildren() - 1;
child = node.GetChildAt(lastChildIndex, true);
return(GetBiggest(child, delete));
}
NeoDatis.Btree.IKeyAndValue kav = node.GetKeyAndValueAt(lastKeyIndex);
if (delete)
{
node.DeleteKeyAndValueAt(lastKeyIndex, false);
persister.SaveNode(node);
}
return(kav);
}
/// <summary>
/// <pre>
/// 1 take median element
/// 2 insert the median in the parent (shifting necessary elements)
/// 3 create a new node with right part elements (moving keys and values and children)
/// 4 set this new node as a child of parent
/// </pre>
/// </summary>
public virtual void Split(NeoDatis.Btree.IBTreeNode parent, NeoDatis.Btree.IBTreeNode
node2Split, int childIndex)
{
// BTreeValidator.validateNode(parent, parent == root);
// BTreeValidator.validateNode(node2Split, false);
// 1
NeoDatis.Btree.IKeyAndValue median = node2Split.GetMedian();
// 2
parent.SetKeyAndValueAt(median, childIndex, true, true);
// 3
NeoDatis.Btree.IBTreeNode rightPart = node2Split.ExtractRightPart();
// 4
parent.SetChildAt(rightPart, childIndex + 1);
parent.SetChildAt(node2Split, childIndex);
parent.IncrementNbChildren();
persister.SaveNode(parent);
persister.SaveNode(rightPart);
persister.SaveNode(node2Split);
if (NeoDatis.Btree.Tool.BTreeValidator.IsOn())
{
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(parent, parent == root);
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(rightPart, false);
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(node2Split, false);
}
}
private void BuildDisplay(NeoDatis.Btree.IBTreeNode node, int currentHeight, int
childIndex, object parentId, bool withIds)
{
if (currentHeight > lines.Length - 1)
{
return;
}
// get string buffer of this line
System.Text.StringBuilder line = lines[currentHeight];
if (withIds)
{
line.Append(node.GetId()).Append(":[");
}
else
{
line.Append("[");
}
for (int i = 0; i < node.GetNbKeys(); i++)
{
if (i > 0)
{
line.Append(" , ");
}
NeoDatis.Btree.IKeyAndValue kav = node.GetKeyAndValueAt(i);
line.Append(kav.GetKey());
}
if (withIds)
{
line.Append("]:").Append(node.GetParentId()).Append("/").Append(parentId).Append(
" ");
}
else
{
line.Append("] ");
}
for (int i = 0; i < node.GetNbChildren(); i++)
{
NeoDatis.Btree.IBTreeNode child = node.GetChildAt(i, false);
if (child != null)
{
BuildDisplay(child, currentHeight + 1, i, node.GetId(), withIds);
}
else
{
lines[currentHeight + 1].Append("[Child " + (i + 1) + " null!] ");
}
}
}
public virtual object DeleteKeyForLeafNode(NeoDatis.Btree.IKeyAndValue keyAndValue
)
{
int position = GetPositionOfKey(keyAndValue.GetKey());
if (position < 0)
{
return(null);
}
int realPosition = position - 1;
object value = values[realPosition];
LeftShiftFrom(realPosition, false);
nbKeys--;
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(this);
return(value);
}
private static void CheckValuesOfChild(NeoDatis.Btree.IKeyAndValue key, NeoDatis.Btree.IBTreeNode
node)
{
if (!on)
{
return;
}
if (node == null)
{
return;
}
for (int i = 0; i < node.GetNbKeys(); i++)
{
if (node.GetKeyAndValueAt(i).GetKey().CompareTo(key.GetKey()) >= 0)
{
throw new NeoDatis.Btree.Exception.BTreeNodeValidationException("Left child with values bigger than pivot "
+ key + " : " + node.ToString());
}
}
}
public virtual NeoDatis.Btree.IKeyAndValue GetSmallest(NeoDatis.Btree.IBTreeNode
node, bool delete)
{
if (!node.IsLeaf())
{
NeoDatis.Btree.IBTreeNode child = node.GetChildAt(0, true);
if (child.GetNbKeys() == degree - 1)
{
node = PrepareForDelete(node, child, 0);
}
child = node.GetChildAt(0, true);
return(GetSmallest(child, delete));
}
NeoDatis.Btree.IKeyAndValue kav = node.GetKeyAndValueAt(0);
if (delete)
{
node.DeleteKeyAndValueAt(0, true);
persister.SaveNode(node);
}
return(kav);
}
public override object DeleteKeyForLeafNode(NeoDatis.Btree.IKeyAndValue keyAndValue
)
{
bool objectHasBeenFound = false;
int position = GetPositionOfKey(keyAndValue.GetKey());
if (position < 0)
{
return(null);
}
int realPosition = position - 1;
// In Multiple Values per key, the value is a list
System.Collections.IList value = (System.Collections.IList)values[realPosition];
// Here we must search for the right object. The list can contains more than 1 object
int size = value.Count;
for (int i = 0; i < size && !objectHasBeenFound; i++)
{
if (value[i].Equals(keyAndValue.GetValue()))
{
value.Remove(i);
objectHasBeenFound = true;
}
}
if (!objectHasBeenFound)
{
return(null);
}
// If after removal, the list is empty, then remove the key from the node
if (value.Count == 0)
{
// If we get there
LeftShiftFrom(realPosition, false);
nbKeys--;
}
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(this);
return(keyAndValue.GetValue());
}
public virtual void SetKeyAndValueAt(NeoDatis.Btree.IKeyAndValue keyAndValue, int
index, bool shiftIfAlreadyExist, bool incrementNbKeys)
{
SetKeyAndValueAt(keyAndValue.GetKey(), keyAndValue.GetValue(), index, shiftIfAlreadyExist
, incrementNbKeys);
}
public virtual void SetKeyAndValueAt(NeoDatis.Btree.IKeyAndValue keyAndValue, int
index)
{
SetKeyAndValueAt(keyAndValue.GetKey(), keyAndValue.GetValue(), index);
}
/// <summary>Returns the value of the deleted key</summary>
/// <param name="node"></param>
/// <param name="keyAndValue"></param>
/// <returns></returns>
/// <exception cref="System.Exception">System.Exception</exception>
protected virtual object InternalDelete(NeoDatis.Btree.IBTreeNode node, NeoDatis.Btree.IKeyAndValue
keyAndValue)
{
int position = node.GetPositionOfKey(keyAndValue.GetKey());
bool keyIsHere = position > 0;
int realPosition = -1;
NeoDatis.Btree.IBTreeNode leftNode = null;
NeoDatis.Btree.IBTreeNode rightNode = null;
try
{
if (node.IsLeaf())
{
if (keyIsHere)
{
object deletedValue = node.DeleteKeyForLeafNode(keyAndValue);
GetPersister().SaveNode(node);
return(deletedValue);
}
// key does not exist
return(null);
}
if (!keyIsHere)
{
// descend
realPosition = -position - 1;
NeoDatis.Btree.IBTreeNode child = node.GetChildAt(realPosition, true);
if (child.GetNbKeys() == degree - 1)
{
node = PrepareForDelete(node, child, realPosition);
return(InternalDelete(node, keyAndValue));
}
return(InternalDelete(child, keyAndValue));
}
// Here,the node is not a leaf and contains the key
realPosition = position - 1;
System.IComparable currentKey = node.GetKeyAt(realPosition);
object currentValue = node.GetValueAsObjectAt(realPosition);
// case 2a
leftNode = node.GetChildAt(realPosition, true);
if (leftNode.GetNbKeys() >= degree)
{
NeoDatis.Btree.IKeyAndValue prev = GetBiggest(leftNode, true);
node.SetKeyAndValueAt(prev, realPosition);
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(node, node == root);
GetPersister().SaveNode(node);
return(currentValue);
}
// case 2b
rightNode = node.GetChildAt(realPosition + 1, true);
if (rightNode.GetNbKeys() >= degree)
{
NeoDatis.Btree.IKeyAndValue next = GetSmallest(rightNode, true);
node.SetKeyAndValueAt(next, realPosition);
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(node, node == root);
GetPersister().SaveNode(node);
return(currentValue);
}
// case 2c
// Here, both left and right part have degree-1 keys
// remove the element to be deleted from node (shifting left all
// right
// elements, link to right link does not exist anymore)
// insert the key to be deleted in left child and merge the 2 nodes.
// rightNode should be deleted
// if node is root, then leftNode becomes the new root and node
// should be deleted
//
node.DeleteKeyAndValueAt(realPosition, true);
leftNode.InsertKeyAndValue(currentKey, currentValue);
leftNode.MergeWith(rightNode);
// If node is the root and is empty
if (!node.HasParent() && node.GetNbKeys() == 0)
{
persister.DeleteNode(node);
root = leftNode;
leftNode.SetParent(null);
// The height has been decreased. No need to save btree here.
// The calling delete method will save it.
height--;
}
else
{
node.SetChildAt(leftNode, realPosition);
// Node must only be validated if it is not the root
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(node, node == root);
}
persister.DeleteNode(rightNode);
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(leftNode, leftNode == root);
GetPersister().SaveNode(node);
GetPersister().SaveNode(leftNode);
return(InternalDelete(leftNode, keyAndValue));
}
finally
{
}
}
private NeoDatis.Btree.IBTreeNode PrepareForDelete(NeoDatis.Btree.IBTreeNode parent
, NeoDatis.Btree.IBTreeNode child, int childIndex)
{
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(parent);
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(child);
// case 3a
NeoDatis.Btree.IBTreeNode leftSibling = null;
NeoDatis.Btree.IBTreeNode rightSibling = null;
try
{
if (childIndex > 0 && parent.GetNbChildren() > 0)
{
leftSibling = parent.GetChildAt(childIndex - 1, false);
}
if (childIndex < parent.GetNbChildren() - 1)
{
rightSibling = parent.GetChildAt(childIndex + 1, false);
}
// case 3a left
if (leftSibling != null && leftSibling.GetNbKeys() >= degree)
{
NeoDatis.Btree.IKeyAndValue elementToMoveDown = parent.GetKeyAndValueAt(childIndex
- 1);
NeoDatis.Btree.IKeyAndValue elementToMoveUp = leftSibling.GetLastKeyAndValue();
parent.SetKeyAndValueAt(elementToMoveUp, childIndex - 1);
child.InsertKeyAndValue(elementToMoveDown.GetKey(), elementToMoveDown.GetValue());
if (leftSibling.GetNbChildren() > leftSibling.GetNbKeys())
{
// Take the last child of the left sibling and set it the
// first child of the 'child' (incoming parameter)
// child.setChildAt(leftSibling.getChildAt(leftSibling.getNbChildren()
// - 1, true), 0);
child.SetChildAt(leftSibling, leftSibling.GetNbChildren() - 1, 0, true);
child.IncrementNbChildren();
}
leftSibling.DeleteKeyAndValueAt(leftSibling.GetNbKeys() - 1, false);
if (!leftSibling.IsLeaf())
{
leftSibling.DeleteChildAt(leftSibling.GetNbChildren() - 1);
}
persister.SaveNode(parent);
persister.SaveNode(child);
persister.SaveNode(leftSibling);
if (NeoDatis.Btree.Tool.BTreeValidator.IsOn())
{
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(parent, parent == root);
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(child, false);
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(leftSibling, false);
NeoDatis.Btree.Tool.BTreeValidator.CheckDuplicateChildren(leftSibling, child);
}
return(parent);
}
// case 3a right
if (rightSibling != null && rightSibling.GetNbKeys() >= degree)
{
NeoDatis.Btree.IKeyAndValue elementToMoveDown = parent.GetKeyAndValueAt(childIndex
);
NeoDatis.Btree.IKeyAndValue elementToMoveUp = rightSibling.GetKeyAndValueAt(0);
parent.SetKeyAndValueAt(elementToMoveUp, childIndex);
child.InsertKeyAndValue(elementToMoveDown.GetKey(), elementToMoveDown.GetValue());
if (rightSibling.GetNbChildren() > 0)
{
// Take the first child of the right sibling and set it the
// last child of the 'child' (incoming parameter)
child.SetChildAt(rightSibling, 0, child.GetNbChildren(), true);
child.IncrementNbChildren();
}
rightSibling.DeleteKeyAndValueAt(0, true);
persister.SaveNode(parent);
persister.SaveNode(child);
persister.SaveNode(rightSibling);
if (NeoDatis.Btree.Tool.BTreeValidator.IsOn())
{
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(parent, parent == root);
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(child, false);
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(rightSibling, false);
NeoDatis.Btree.Tool.BTreeValidator.CheckDuplicateChildren(rightSibling, child);
}
return(parent);
}
// case 3b
bool isCase3b = (leftSibling != null && leftSibling.GetNbKeys() == degree - 1) ||
(rightSibling != null && rightSibling.GetNbKeys() >= degree - 1);
bool parentWasSetToNull = false;
if (isCase3b)
{
// choose left sibling to execute merge
if (leftSibling != null)
{
NeoDatis.Btree.IKeyAndValue elementToMoveDown = parent.GetKeyAndValueAt(childIndex
- 1);
leftSibling.InsertKeyAndValue(elementToMoveDown.GetKey(), elementToMoveDown.GetValue
());
leftSibling.MergeWith(child);
parent.DeleteKeyAndValueAt(childIndex - 1, true);
if (parent.GetNbKeys() == 0)
{
// this is the root
if (!parent.HasParent())
{
root = leftSibling;
root.SetParent(null);
height--;
parentWasSetToNull = true;
}
else
{
throw new NeoDatis.Btree.Exception.BTreeNodeValidationException("Unexpected empty node that is node the root!"
);
}
}
else
{
parent.SetChildAt(leftSibling, childIndex - 1);
}
if (parentWasSetToNull)
{
persister.DeleteNode(parent);
}
else
{
persister.SaveNode(parent);
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(parent, parent == root);
}
// child was merged with another node it must be deleted
persister.DeleteNode(child);
persister.SaveNode(leftSibling);
// Validator.validateNode(child, child == root);
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(leftSibling, leftSibling == root);
// Validator.checkDuplicateChildren(leftSibling, child);
if (parentWasSetToNull)
{
return(root);
}
return(parent);
}
// choose right sibling to execute merge
if (rightSibling != null)
{
NeoDatis.Btree.IKeyAndValue elementToMoveDown = parent.GetKeyAndValueAt(childIndex
);
child.InsertKeyAndValue(elementToMoveDown.GetKey(), elementToMoveDown.GetValue());
child.MergeWith(rightSibling);
parent.DeleteKeyAndValueAt(childIndex, true);
if (parent.GetNbKeys() == 0)
{
// this is the root
if (!parent.HasParent())
{
root = child;
root.SetParent(null);
height--;
parentWasSetToNull = true;
}
else
{
throw new NeoDatis.Btree.Exception.BTreeNodeValidationException("Unexpected empty root node!"
);
}
}
else
{
parent.SetChildAt(child, childIndex);
}
if (parentWasSetToNull)
{
persister.DeleteNode(parent);
}
else
{
persister.SaveNode(parent);
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(parent, parent == root);
}
persister.DeleteNode(rightSibling);
persister.SaveNode(child);
NeoDatis.Btree.Tool.BTreeValidator.ValidateNode(child, child == root);
// Validator.validateNode(rightSibling, rightSibling ==
// root);
// Validator.checkDuplicateChildren(rightSibling, child);
if (parentWasSetToNull)
{
return(root);
}
return(parent);
}
throw new NeoDatis.Btree.Exception.BTreeNodeValidationException("deleting case 3b but no non null sibling!"
);
}
}
finally
{
}
throw new NeoDatis.Btree.Exception.BTreeNodeValidationException("Unexpected case in executing prepare for delete"
);
}
